In general, a suspension for an automobile is provided between a chassis of the automobile and a wheel and configured to elastically support a load of the chassis of the automobile and absorb vibration transferred from the wheel to the chassis of the automobile.
As one example of the suspension for an automobile, Macpherson type suspension includes a shock absorber. The shock absorber includes a strut tube connected to the wheel and a strut rod provided to be vertically movable within the strut tube and connected to the chassis of the automobile. When the strut rod is inserted into the strut tube by vibration transferred from the wheel to the chassis of the automobile, a shock is absorbed.
Further, a lower spring sheet is fixed at a peripheral surface of the strut tube, an insulator configured to connect the strut rod to the chassis of the automobile is combined with an upper end of the strut rod, and a rolling bearing is provided under the insulator. Furthermore, an upper spring sheet is arranged under the rolling bearing. A coil-shaped spring is provided between the upper spring sheet and the lower spring sheet. When the shock absorber is operated, the spring is compressed and thus absorbs the vibration.